Search found 273 matches

by Andrew (grayhat)
Fri May 05, 2023 8:18 am
Forum: Questions & Advice
Topic: any reasonably-sized directional antennas for FM broadcast radio reception?
Replies: 5
Views: 14282

Re: any reasonably-sized directional antennas for FM broadcast radio reception?

Recently, I became interested in chasing down some low-power community FM broadcast stations. Yes, I know it is possible to build yagis to cover the commercial FM broadcast range, but I was hoping for something more compact and more readily portable... Cheers, Jock Hi there, Jock, you may try the &...
by Andrew (grayhat)
Fri May 05, 2023 7:48 am
Forum: General Discussion
Topic: What's the best-looking shortwave tabletop receiver?
Replies: 41
Views: 77772

Re: What's the best-looking shortwave tabletop receiver?

just found a nice and pretty "rare" receiver https://wa3dsp.org/RME/RME6900/ https://wa3dsp.org/RME/RME6900/DSC04617.JPG according to the notes found at the above link, RME was a small company created by W9CI and W9RGH, after WW2 they merged with Electrovoice and later on, the Ten Tec comp...
by Andrew (grayhat)
Mon May 01, 2023 11:39 am
Forum: General Discussion
Topic: One antenna, multiple receivers...
Replies: 0
Views: 29233

One antenna, multiple receivers...

... or even, multiple antennas, one receiver :D Anyhow, the following device https://ka7oei.blogspot.com/2019/11/homebrew-construction-of-2-and-4-port.html?m=1 is called splitter/combiner, they exist as passive or active ones, the above one has pretty good insertion loss, but willing to compensate i...
by Andrew (grayhat)
Fri Apr 21, 2023 12:01 pm
Forum: General Discussion
Topic: Matching transformer for random wire?
Replies: 7
Views: 14401

Re: Matching transformer for random wire?

Oh and as for the ATU check out this one https://pa0fri.home.xs4all.nl/ATU/FRImatch/FRImatcheng.htm for RX only (or for QRP use) it can be built using a pair of polyvaricons https://pa0fri.home.xs4all.nl/ATU/FRImatch/pa4mf1.jpg also, while the original design covers the range between 3 and 30 MHz, w...
by Andrew (grayhat)
Fri Apr 21, 2023 10:29 am
Forum: General Discussion
Topic: Matching transformer for random wire?
Replies: 7
Views: 14401

Re: Matching transformer for random wire?

forgot, if you want to build your own impedance transformer, it's easy, just follow the directions here http://www.aytechnologies.com/TechData/9-to-1_XFMR.htm as for the core, 77, 73 and 43 materials will be ok, one turn is counted each time the two ends of the wire enter the binocular holes and exi...
by Andrew (grayhat)
Fri Apr 21, 2023 8:30 am
Forum: General Discussion
Topic: Matching transformer for random wire?
Replies: 7
Views: 14401

Re: Matching transformer for random wire?

willing to avoid an ATU and to have a better S/N ratio, you may consider putting up a different type of antenna, I'm referring to the T2FD https://cdn-bio.qrz.com/b/vk2evb/Home_Brew_T2FD.jpg?p=baf653982e2e9d35e4b85b25d46b36fe it's basically a folded dipole with a termination resistor, it can be easi...
by Andrew (grayhat)
Wed Apr 19, 2023 3:43 pm
Forum: General Discussion
Topic: Matching transformer for random wire?
Replies: 7
Views: 14401

Re: Matching transformer for random wire?

A good size for a random is an 84ft antenna wire and a 17ft counterpoise wire, to connect them to the coax you may use this 9:1 https://www.nooelec.com/store/balun-one-nine-v2-barebones.html enclosed in a small weatherproof box, add an adapter to connect the SMA to whatever coax connector you use (I...
by Andrew (grayhat)
Wed Apr 19, 2023 3:31 pm
Forum: General Discussion
Topic: Matching transformer for random wire?
Replies: 7
Views: 14401

Re: Matching transformer for random wire?

I'm having good luck with my End-fedz SWL antenna but I want to experiment with a longer-wire version of that general approach. I have an old Radio Shack random wire SWL antenna and I want to feed the receivers with coax, so some kind of unun transformer seems correct. Is there a proper ratio that ...
by Andrew (grayhat)
Mon Apr 10, 2023 6:19 am
Forum: General Discussion
Topic: Improving the MLA-30
Replies: 2
Views: 11612

Re: Improving the MLA-30

Yep Egil, know that, all in all I wrote that post :D
by Andrew (grayhat)
Wed Apr 05, 2023 7:21 pm
Forum: General Discussion
Topic: Improving the MLA-30
Replies: 2
Views: 11612

Improving the MLA-30

Here are some suggestions, in case you decided to buy it, that is :) First step, improve the loop; either use some copper pipe or alumium strip to make a wider and BIGGER loop (easy) Second step; match the impedance, the preamp has an impedance ranging from 1.5K down to 450Ohm, now ler's find a bala...